Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261396AbVAMDlW (ORCPT ); Wed, 12 Jan 2005 22:41:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261405AbVAMDlW (ORCPT ); Wed, 12 Jan 2005 22:41:22 -0500 Received: from gate.crashing.org ([63.228.1.57]:22425 "EHLO gate.crashing.org") by vger.kernel.org with ESMTP id S261396AbVAMDlR (ORCPT ); Wed, 12 Jan 2005 22:41:17 -0500 Subject: Re: [PATCH] ppc64: xtime <-> gettimeofday can get out of sync From: Benjamin Herrenschmidt To: Anton Blanchard Cc: Andrew Morton , Paul Mackerras , Linux Kernel list In-Reply-To: <20050110132429.GS14239@krispykreme.ozlabs.ibm.com> References: <20050110132429.GS14239@krispykreme.ozlabs.ibm.com> Content-Type: text/plain Date: Thu, 13 Jan 2005 14:40:55 +1100 Message-Id: <1105587656.27435.10.camel@gaston> Mime-Version: 1.0 X-Mailer: Evolution 2.0.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 859 Lines: 22 > Note that the time_sync_xtime check only stops the seconds from going > backwards, the ns component still could couldnt it? Considering this > is hard to get right, should we switch to the time interpolator stuff? > The only problem there is it might be trouble for systemcfg (which > exports stuff to do userspace gettimeofday). My userland implementation in the vDSO also relies on our current algorithm. It's not merged yet and could be changed of course, but I ended up quite liking our current code ;) The interesting thing with it is we are basically lock-less (and even barrier-less on reads). Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/